This invention is generally directed to developer compositions, and more specifically the present invention is directed to developer compositions, and toner compositions, which contain therein as negative charge enhancing additives certain diaryl or dialkyl sulfonimides. In one embodiment of the present invention there is thus provided toner compositions comprised of resin particles, pigment particles, and dibenzene sulfonimides as negative charge enhancing additives. The sulfonimides impart a negative charge to the toner resin particles, allowing the resulting developer compositions to be selected for use in the development of colored xerographic images.
There is disclosed in the prior art the use of charge control materials for the purpose of providing a positive charge to the toner resin particles. Thus, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium compounds as charge control additives for electrostatic toner compositions. Additionally, there is disclosed in U.S. Pat. No. 4,298,672, toner compositions containing as positive charge enhancing additives alkyl pyridinium halides, including cetyl pyridinium chloride. Further described in U.S. Pat. No. 4,338,390 are toner compositions including therein as a positive charge enhancing additive various organic sulfate or sulfonates, such as stearyl dimethyl phenethyl ammonium tosylate.
Furthermore, disclosed in copending applications are toner and developer compositions containing as charge enhancing additives orthohalophenylcarboxylic acids, which additives impart a negative charge to the toner resin particles, and negatively charged toner compositions having incorporated therein aryl sulfones. While other negative charge controlling additives may be known, there nevertheless continues to be a need for the development of new negative charge enhancing additives. Additionally, there is a need for toner compositions containing negative charge enhancing additives wherein there is imparted in a rapid time period high negative charges to the toner resin particles. Furthermore, there continues to be a need for colored developer compositions containing therein negative charge enhancing additives which do not adversely affect the colored pigments, such as magenta, cyan and/or yellow compositions contained therein.